[dewayne]

Hello Gents,
I am interested in joining in as well here and coming uo with a GEKO clone. Does anyone have any schematics, PCB layouts and firmware to get me started out with,

Cheers from the Wet UK

[bsharp]

About a year ago I had posted a thread on doing something like this. I have now gotten other projects out of the way and I am diving back into this one. I have done a lot of reading about building H bridges as this is the most daunting task for me. I have looked over many types posted around the internet and I think I know enough to be dangerous and cause bodily harm. It looks to me like an all N channel bridge using IR2104 “type” drivers is the way to go. I am looking at building something that could scale to high voltage if needed. To start out with I am going to use some RFP40N10 because they are inexpensive “free ripped from old UPS” because I will more than likely toast a few before I get it right. As far as the Programming goes I remember I modified quite a few things in the code. Initially I was going to have the dsPIC set the direction on one pin and do the PWM on another latched together with shoot through protection. I also wanted to add a section to set a value for adjusting the current from the dsPIC. And ultimately add all the features of an industrial quality drive like short circuit protection, over and under current and such with a nice little Windows app to tune and configure the drive. But I got to get the H Bridge working and then go from there. As soon as the Fet drivers show up I will start playing around on the bench and see what damage I can cause. If I get crazy enough this just may work. :banana:

[MaX-MoD]

Hi, I have modified the firmware to use a discrete H-bridge.
Currently, i am testing the first (non-breadboarded) proto.
It's running fine with IRF540
You can find more infos (only in French, sorry!) on my website and on usinages.com (see the tread)

I will post the modified firmware and PCB (KiCAD files) when its all clean
English manual will also come soon.

[BillTodd]

MaX-Mod,

C'est fantastique! (I've been hoping someone would get this to work, so i could build one or three )

[tecfacet]

hello,

i am looking forward to seeing the code for this servo project. this is something that i have been looking to do for a long time.

is there anything i can do to help ??

roger

[BillTodd]

Max-Mod,

How's progress?

[MaX-MoD]

Hello,
I apologise for that long silence, I've been quite busy.
The source is here : dspic-servo-26-Oct-2008.zip
and the KiCAD project (TO220 MOSFET, NCP5106 driver, no SMT parts) : V1.zip
And finally the manual, in French : YAPSC-Manuel

PS:
Forgot to say the board runs fine. I don't think there will be any other improvements, maybe just error loop between controllers (all controllers stop in the cas of one detects a MaxError event reached)

I am planning a smaller, simple board without power stage, in order to control +-10V servo amplifiers directly.
I am also starting the native 3 phase controller for AC and BLDC :rainfro:

[BillTodd]

Great news Max-Mod


Typical! I broke the glass encoder one of my servo motors this afternoon!

[MaX-MoD]

arf, bad news.
Murphy always gets you when you don't wait for him. Always.

[BillTodd]

Max-Mod,

Are the NCP5106 type A or type B (with cross conduction prevention circuit)?

[MaX-MoD]

Wich one you like the best.
The dsPIC has integrated dead time so...
But depending in the MOS you'll use, you may have to change the dead time value.

Oh, and you can use IR's pin-to-pin compatible drivers instead of NCP5106

[smarbaga]

Hello
I have attached a somewhat layout of the Lawrence Glaister dspic servo controller.
the motor parameters are set via the usb port.
the motor maximum current is set digitally also via usb.
as you can see this setup is using an H_bridge instead of amplifiers.
I have used the current monitor and usb chips in other ccts, works good.

I have to match the component names and numbers with the schematic and
make the power traces a bit wider.
I have to bench test a complete unit before ant pcb's will be made.
when this is done i will post the complete schematic and latout.
Garry

[MaX-MoD]

nice compact design smarbaga!
I guess you will have the boards professionnaly manufactured, right?
but... the USB bus traces are pretty close to the motor's power output!
considering the enormous current spikes and noise in these traces, is there any deconnection or errors with USB when powered???

PS:
waiting for the schematics
I am curious about the current sense

[BillTodd]

but... the USB bus traces are pretty close to the motor's power output

!
Oh yes!

Route them either side of the GND pin and consider using a GND guard trace between them and the Motor nets.

[smarbaga]

Hello
i know the usb traces are close to the dc lines
i had a few choices, but because the usb is only used to set the cpu's parameters
there will be no motor action and no dc current draw to the motor.
after the cpu's parameters are set , pid, max. current etc.., the usb will be dead
or idle untill next power up or reset.
thanks for pointing out the trace spacing.
attached: untested schematic and proposed pcb.
garry

[samco]

The http://www.zetex.com/3.0/pdf/ZXCT1081.pdf chip only seems to work up to 40v.. (if I am reading that right - max motor supply would be 40v or there abouts.)

(I love the idea of high side sensing.)

sam

[BillTodd]

the usb will be dead

So will your USB port if there's any kind of short/spike/cock-up

Just route the traces up and around the GND pin and add a Gnd trace between them and the motor traces. Do it now, before you kill your USB port.

[smarbaga]

thanks Mr billtodd, i will put the isb data lines around the gnd term.
the 2 res r19 +r20 let the zxct chip work at a higher voltage.
i had that working in another cct at 100 volts, and the chips worked fine.
the zxct chip has a very linear output , analog 0 to 4.5 volts , amps proportional.

[arisov77]

thanks Mr billtodd, i will put the isb data lines around the gnd term.
the 2 res r19 +r20 let the zxct chip work at a higher voltage.
i had that working in another cct at 100 volts, and the chips worked fine.
the zxct chip has a very linear output , analog 0 to 4.5 volts , amps proportional.

On my, this all as that unreliable. Today works, but tomorrow?

I have put(deliver)ed the optocouplers on Step/Dir. For low supplying motor of the engines possible all will work, but under high supplying voltages of the hindrance above and can be a malfunction.

Also possible converter USB/UART to move in DataCable, since usually do several servocontrollers, that economy FT232R and place on PCB. I did such here http://www.cnczone.com/forums/showthread.php?t=69640. But beside me why that with USB/UART bad works (long unites ). In russian forum I have advised the optocouplers on ADuMxx. I did not try.

Else has put(deliver)ed the quartz high. The Speed will not disturb. On model well, but on real tool, it is necessary very quick reaction on mechanical loads.

[MaX-MoD]

I have putted optocouplers between the PC (RS232) and the board, to protect the PC during setting of the P, I and D. I do change the parameters on-the-fly to fine tune (ears-tune ) parameters while the motor turns... and problems could happend!

So why nobody puts optocouplers between the configuration port and the PC????

Also possible converter USB/UART to move in DataCable, since usually do several servocontrollers, that economy FT232R and place on PCB.

Same idea, man